Community Interactions And Sucession

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Text of Community Interactions And Sucession

  • 1. Community Interactions

2. Community Interactions

  • Powerfully affect an ecosystem
  • Include:
    • Competition
    • Predation
    • Symbiosis
    • Herbivory
    • Disease

3. 4. Interspecific Competition

  • When organisms of the same or different species attempt to use an ecological resource at the same place and the same time
    • Resource any necessity to life
    • Plants and animals compete
    • Winner and losers
    • Grass hoppers and bison
    • Lynx and fox

5. Rules, rules, rules

  • Fundamental rule in ecology
    • Competitive Exclusion Principle
      • No two species can occupy the same niche in the same habitat and the same time
      • Prevents competition
        • Paramecium caudatumandParamecium aurelia
      • Fundamental Niche (potentially occupied)
      • Realized Niche (actually occupied)
      • P 1160

6. How can species coexist in same community?

  • Realized Niche
  • Resource portioning
    • Differentiation of niches that enables species to coexist
    • Different perches
  • Character displacement
    • Tendency for characteristics to be more divergent in sympatric (geo overlapping) populations of two species that allopatric (geog sep) populations of two species
    • Two species with similar niches will make slight changes in body structure and resources they need so they do not compete for resources
      • Finches living on island that are usually very similar have different beaks, one for bigger seeds, one for smaller seeds

7. 8. 9. 10. 11. 12. Predation

  • Interaction where an organism captures and feeds on another organism (+/-)
  • Predator
    • Organism that does the killing and eating
  • Prey
    • Organism that is being killed and eaten (victim)

13. Defenses p. 1162

  • Cryptic coloration
    • Camouflage
  • Aposematic coloration
    • Warning coloration for organisms with effective chemical defenses
  • Batesian mimicry
    • Harmless imitates dangerous
  • Mullerian mimicry
    • 2 or more unpalatable have similar appearance
    • Cukoo bee and yellow jacket
    • Coral snakes and yellow jacketsyellow
  • Predators also use mimicry
    • Turtle tongue

14. 15. 16. 17. 18. 19. Herbivory

  • When a herbivore eats plant or algae (+/-)
  • Large mammals, small invertebrates (insects), marine organisms (sea urchins, snails, fish)
  • Toxic and nontoxic plants
    • Chemical sensors
    • olfactory
  • Specialized teeth and digestive systems
  • Plants defenses
    • Toxins: tannins, nicotine, strychnine
    • Not harmful to humans

20. Symbiosis

  • Any relationship where two species live closely together
  • Symbiosis literally means living together
  • 3 main types
    • Parasitism
    • Mutualism
    • commensalism

21. What type of relationship is this?

  • Who is helping who?

22. Mutualism

  • Both species benefit from the relationship (+/+)
  • A Happy couple
  • Flowers and bees
    • Flowers need bees for pollination, bees need flowers nectar

23. 24. Commensalism

  • One member of the relationship benefits while the other is neither harmed nor helped (+/0)
  • One-sided
  • Food or shelter
  • Barnacles on whale

25. 26. What type of relation ship is going on here?

  • Who is helping who?

27. 28. What type of interaction is going on here? 29. Parasitism

  • One organism lives on or inside another organism and harms it (+/-)
    • Endoparasitism
    • Ectoparasitim
    • Parasitoidism
  • Usually large and multicellular
  • Parasite obtains all or part of its nutrients from the other organism
  • Host
    • Organism that is harmed in relation ship; the one that provides the nutrients to the parasite
  • Parasite
    • Organism that gets its nutrients from the host
  • Do they want to kill their host?
    • No, because they need themmostly annoying

30. 31. 32. 33. Disease

  • Disease causing agents (+/-)
  • Bacteria, viruses, protists, sometimes fungi and prions
  • Most are microscopic
  • Inflict harm on host
  • Not many studies, but they do have an ecological impact
    • Sudden oak death:Phytophthora ramorum
      • 1994-2004
      • Fungus-like protist
      • killed thousands of oak trees from CA to Oregon
    • West Nile virus
      • 1999-2003
      • Killed thousands of birds in US as it spread

34. 35. Recap

  • What are the three types of interactions in a community?
    • Competition
    • Predation
    • Herbivory
    • Disease
    • Symbiosis
      • What types do we have?
        • Mutualism
        • Commensalism
        • Parasitism

36. Interspecific Interactions and Adaptation

  • Coevolution
    • Reciprocal evolutionary adaptations of 2 interacting species
    • Genetic change in one sp. influences genetic change in another sp.
      • Ex. Gene-for-gene recognition in plant and pathogen
    • Aposematic coloration and predators reactions NOT coevolution
      • Across multiple species, not 2 linked population
  • Current hypothesis is that Predation and competition are key factors that control community structure and drive community dynamics
    • Base on temperate and not tropical communities
  • Hypothesis is being challenged

37. Species Diversity

  • Variety of different organisms in a communitydependent on both:
    • Species richness
      • Total # of diff. sp in comm.
    • Relative abundance
      • Portion each sp represent of the total individuals in comm.
  • Example
    • Forest 1 and forest 2, 100 individual
    • Forest 1
      • TreeA25%
      • Tree B 25%
      • Tree C 25%
      • Tree D 25%
    • Forest 2
      • Tree A 80%
      • Tree B 5%
      • Tree C 5%
      • Tree D 10%
      • Forest 1 ismore diverse,even thought both contain 4 types of trees

38. Limits on Food Webs

  • Charles Elton 1920 Oxford Biologist
    • F